More News on Vitamin D and COVID-19
A group of researchers in the U.S. just published a study that adds to the now overwhelming body of evidence linking vitamin D to COVID-19.
This study examined the records of 287 patients who were hospitalized for COVID-19 at Boston University Medical Center from March through August of 2020.
The study had two strengths relative to many previous vitamin D studies:
The researchers only included patients who had a 25D level measured within a year prior to admission. This reduces the likelihood of reverse causality (i.e., that patients with COVID-19 have low 25D levels because the disease suppresses vitamin D). It also addresses the problem we’ve seen with some studies that used 25D measurements from 10+ years prior to hospital admission.
The researchers defined vitamin D sufficiency as >30 ng/mL. Many previous studies have used a cutoff of 20 ng/mL or even 10 ng/mL, which many institutions, including the U.S. National Institutes of Health and the Endocrine Society, would define as deficient.
The findings of this study were remarkable.
After adjustment for confounding factors, patients >65 years old (i.e., those at greatest risk) with 25D levels >30 ng/mL experienced a:
67 percent reduction in mortality
78 percent reduction in acute respiratory distress syndrome (the primary cause of death from COVID-19)
74 percent reduction in severe sepsis
Perhaps most impressively, across all patients with a body mass index (BMI) <30, 25D sufficiency was associated with an 82 percent reduction in mortality!
I want to mention one more important thing about this study.
In obese patients (BMI >30) under 65 years old, the association between serum 25D levels and mortality disappeared. Put another way, obesity seemed to eliminate the protective effect of having normal vitamin D levels in this age group.
Why would this happen?
One possible explanation is that obesity decreases the conversion of 25D, the less active form of vitamin D, to 1,25D, the more active form. Prior research has suggested people who are obese may need higher amounts of vitamin D (whether through sun exposure, food, or supplements) and perhaps higher serum levels of 25D to maintain sufficient biological vitamin D activity.
This may be another reason why obesity significantly increases the risk of hospitalization and death from COVID-19. And it could give us an important tool—treatment with vitamin D—for reducing the excess risk in obese people.
It is easy to check your Vitamin D status with a blood draw. Probably best to be in the 40-60 range.
If you haven’t tested, do NOT take high doses of Vitamin D. There is such a thing as toxicity. And you can cause an imbalance with other fat-soluble vitamins such as A and K. If you don’t know your level, it is considered safe to supplement 1000-2000iu/day.
Let me know if you would like to check your Vitamin D levels or otherwise address your health. I would love to help.